One problem in the launching and recovery of boats on vessels is that, because of the difference in size, the vessel and the boat move differently in the water. As a result, there will be large relative movements between the vessel and the boat. In addition, waves are often built up to a greater height along the side of the vessel than they would otherwise do, which gives additional large relative movements between the vessel and the boat.
Today, boats on board vessels are normally suspended in davits with whose aid the boats are launched in the water. Conventional davits are primarily intended for launching and function less satisfactorily when retrieving a boat in a high sea. On some vessels, a crane may be used for launching and recovery of a boat.
Lifeboats are normally suspended at two points by wires operated by the davit winch. In a number of systems for pick-up of boats, a single-point attachment is employed. When, on launching and recovery of a boat, hooks are attached or released from the boat, there is a risk that the generally heavy hooks and blocks connected to them may hit the boat because of the large relative movement between the vessel and the boat. Moreover, in systems employing two lifting points, there is the risk that only one hook is disengaged/engaged, in which event the boat runs the risk of being left hanging vertically along the side of the vessel, depending upon what direction the relative vertical movement between the boat and the vessel takes. Even if the crew is successful in attaching or disengaging the hooks from the boat, there is moreover the risk that wires are slack to such an extent that these hit the boat. This applies as long as the boat has not been raised free above the crests of the waves.
If the mother vessel is to be kept under control, it must be under way somewhat in a forward direction, which entails that the engagement and disengagement operations as described above must be able to be put into effect while moving forwards. This makes it even more difficult to execute a launching or recovery operation of a boat using the conventional systems.
There is, thus, a need in the art for a system for the launching and recovery of boats in which the above-outlined drawbacks are obviated or at least reduced to a minimum.